-esSysTmr_T is defined in kernel_cfg.h since both kernel.h and cpu.h
needs it
-Various refactoring to better reflect function responsibility
-portSysTmrIsr*() only enable/disable interrupts
-added new macro PORT_CRITICAL_EXIT_SLEEP() - this name better describes
what it should do
-some reorganization of internal functions
-esThdTerm() is done
-some doxygen formatting